Why do these birds live in the Qinghai-Tibet Plateau?

the birds of the long-tailed are all cute in good shape. As a close-up species, the brown long-tailed and red-headed long-tailed look very similar except for the different colors of wearing on their ers. However, the two birds live in very different environments. Brown-tailed live at high altitudes of about 2000 to 3000 meters and come and go freely in the special environment of the Qinghai-Tibet Plateau, while red-headed long-tailed prefer the mountains and thickets at low altitudes.
is the difference under a similar appearance? Recently, two researchers from the Institute of Zoology of the Chinese Academy of Sciences, Lei Fumin and Qu Yanhua, revealed the genetic mechanisms of the adaptation of three species of highland birds to high altitudes, the results of which were published in the Proceedings of the National Academy of Sciences.Qinghai-Tibet Plateau is the highest and largest plateau in the world, with an average altitude of 4500 meters. High altitudes are highly oxygen-deprived, low-temperature and ultraviolet radiation, and living conditions are very poor. Mammals and birds that live here are more resistant to cold, oxygen-resistant, metabolic, etc., and gain weight.
Just last year, lei Fumin's team published a study in the Proceedings of the National Academy of Sciences that showed an increase in hemoglobin oxygen affinity in high-altitude birds on the Qinghai-Tibet Plateau compared to their low-altitude near-edge species by comparing the functional esoplots and molecular structures of hemoglobin. Most of these functional changes are caused by different amino acid substitutions.
past research on the biological adaptability of plateaus has mostly focused on esophology, such as size, structural morphology, metabolic rate, etc. "This time we'd like to reveal the genetic mechanisms behind the convergence and evolution of these adaptive traits at a molecular level, " Yan Yan, the paper's first author and ph.D. student, told China Science.
they selected three species of bird-shaped birds from the high-altitude areas of the Qinghai-Tibet Plateau - brown-crowned, black-crowned, and brown-tailed - and identified three near-lying low-altitude species that had the same genetic distance as each of them ( controlling the effects of different evolutionary times on genetic adaptation ) - swamp, yellow-bee and red-headed long-tailed.
researchers sequenced five tissues of the heart, muscle, liver, lungs and kidneys of the six birds and compared differences in sequence and expression levels between high- and low-altitude species.By comparing more than 7,000 genes in these birds, the researchers found that three high-altitude bird species shared as many as 218 so-called "positive selection genes" -- genes that allow birds to improve their ability to survive or reproduce in special conditions at high altitudes.
scientists also speculate whether, in addition to genetic variations, the replacement of certain amino acids has also contributed to the birds' ability to adapt to their highland life. But they later found that only four of the three high-altitude species contained the same amino acid replacement points.
" results show that the high-altitude adaptive convergence of these birds is mainly reflected in the positive selection of gene levels, rather than amino acid replacement levels. Yan Yan said.
usually in multiple tissues of different species, there are two patterns of tissue-specific expression and species-specific expression.
so-called "tissue-specific expression" model means that gene expression in the same tissue in different species should be more similar than in different tissues within the same species. The "species-specific expression" model means that gene expression in different tissues within the same species should be more similar than the same tissue between species.
researchers conducted a cluster analysis of patterns of gene expression in all tissues. These same tissue data from different birds are gathered together, indicating general tissue-specific expression patterns. In other words, there are strong similarities in gene expression in the same tissue in different species of birds, suggesting that tissue differentiation may predated species differentiation.
the expression spectrum of differential expression genes and altitude-related gene sets presents altitude-related clustering patterns, suggesting that high-altitude environments may drive similar expression changes in high-altitude species.
results reveal that three species of high-altitude birds may have evolved into environmental adaptations in a way that altered sequence and expression levels.Qu Yanhua, one of the authors of the
paper newsletter, told China Science Daily, "Unlike studies of high-altitude adaptation of other groups, our study is the first to carry out a multi-species, multi-tissue, multi-scale comparative analysis of wild birds with different kinship, expanding people's understanding of how species respond to high-altitude environments." Comparing
with the general convergence of sexual evolution, the adaptive evolution of genetics is more influenced by systemic developmental relationships (i.e., the similarity of genetic background). This phenomenon applies not only to birds, but also to animal groups. She said.
doi:10.1073/pnas.1819657116